Devices for imaging body cavities or passages in vivo are known in the art and include endoscopes and autonomous encapsulated cameras. Endoscopes are flexible or rigid tubes that pass into the body through an orifice or surgical opening, typically into the esophagus via the mouth or into the colon via the rectum. An image is formed at the distal end using a lens and transmitted to the proximal end, outside the body, either by a lens-relay system or by a coherent fiber-optic bundle. A conceptually similar instrument might record an image electronically at the distal end, for example using a CCD or CMOS array, and transfer the image data as an electrical signal to the proximal end through a cable. Because of the difficulty traversing a convoluted passage, endoscopes cannot reach the majority of the small intestine and special techniques and precautions, that add cost, are required to reach the entirety of the colon. Capsule endoscope is an alternative in vivo image sensor that addresses many of these problems. A camera is housed in a swallowable capsule, along with a radio transmitter for transmitting data, primarily comprising images recorded by the digital camera, to a base-station receiver or transceiver and data recorder outside the body. Another autonomous capsule camera system with on-board data storage was disclosed in the U.S. patent application Ser. No. 11/533,304, filed on Sep. 19, 2006.
A typical procedure of imaging the gastrointestinal tract based on a wireless capsule camera consists of an inpatient visit in the morning during which a clinician attaches the base station apparatus to the patient and the patient swallows the capsule. The system records images beginning just prior to swallowing and records images of the gastrointestinal (GI) tract until its battery becomes fully discharged. For the system based on an autonomous capsule camera, the images captured will be stored in on-board memory and there is no need to attach a base station to the patient. After the capsule camera is swallowed, peristalsis propels the capsule through the GI tract. The rate of passage depends on the degree of motility. Usually, the small intestine is traversed in 4 to 8 hours. It takes longer to travel through the entire GI tracts. In order to reduce the procedure time for examining the colon, medication is needed to increase the transit speed. Some patients have known slow transit speed and in general the transit time is even long while a patient is sleeping. It is desirable that a means for reducing the procedure time by applying an electrical stimulus to the capsule in vivo. While the capsule camera usually moves in the forward direction (i.e., toward the rectum), it may undergo a retrograde motion occasionally, particularly in the colon. Furthermore, the capsule camera may stay at one place for certain periods of time. Beside the capsule camera, there are other in vivo capsule devices used for various diagnosis and treatment purposes. Other capsule devices also encounter the same issue as the capsule camera. It is desirable to provide an apparatus and method to influence the movement of the capsule device in the GI tract. The capability to influence the movement of the capsule device may offer benefits to broad applications associated with a capsule device.